Nowadays traffic congestion (拥挤，阻塞) is a big problem in most of our cities. Have you got any ideas about what has brought about this?

　　There are many causes for this problem, but the following may be the most important ones.

　　The first cause is the great increase in the number of private cars. Cars take up more space but they carry fewer people. Some private car drivers, ignoring traffic regulations, drive only for the sake of their own convenience, blocking the way of other public transportation vehicles. The second cause is the slow and inefficient construction and improvement of the roads and streets. With a large population and numbers of automobiles increasing, some roads still remain unimproved, which will surely lead to problems. The last cause is the insufficient (不足的) management of the traffic system and the people's lack of awareness of traffic rules. Many pedestrians (行人) cross the streets even when the traffic lights are against them, which is an obstacle (障碍) to the flow of traffic.

　　Then how to solve this problem? Some suggest laying down more roads to make the traffic less crowded and speed up the flow of traffic. Others believe that we should open up more public bus routes, so that more people will take the public buses instead of travelling by car and bicycle.

Though the above two views sound reasonable, they have their own drawbacks. The former may take up much land which could be used for farms and houses. The latter may cause inconvenience for those who are used to travelling by car or bicycle. I think the best answer to the